What is the New American Bible?
The New American Bible (NAB) is an English-language Catholic Bible translation. It is associated with the Confraternity Bible and was first published in 1970. Passages of the Old and New Testaments, taken from the NAB Bible translation, are used in the Lectionary for Mass. (See the Confraternity Bible here.)
The New Testament in the NAB is translated from the original Greek. The Old Testament is translated from the Hebrew language. Like many English Bible translations, books and sections of the Bible appeared in stages, first in 1952 and lastly in 1970. One notable difference is that proper names in the NAB were modified from the traditional Douay-Rheims Catholic translation, reflecting more common renderings. (See Douay-Rheims here.)
Other issues in the NAB
"The New American Bible Revised Edition" updated the language of the Old Testament, especially the Psalms, and modified the New Testament as well. At present the NABRE isn't used in lectionary readings.
The Psalms in the NAB
The book of Psalms has been continually readdressed in the NAB. In 1991 it was modified to reflect gender-neutrality concerning God and people. Gender-neutral references to God weren't permitted for liturgical use, while those referring to people sometimes were. Another edition of the Psalms was completed in 2003, yet was rejected by U.S. bishops. The book was revised again in 2008, but was rejected by the Bishops Committee on Divine Worship.
1. Wikipedia, used under GDFL (with minor edits)